A New Green Approach for Recovery of Metallic Tungsten through Electrolysis of Tungsten Carbide Scrap Anode in Molten Salts

Abstract

In this study, a new green approach has been developed for the recovery of tungsten by using tungsten carbide (WC) scrap material as consumable anode in LiCl-KCl molten salts at 773 K to produce metallic tungsten. The feasibility of the direct electrochemical dissolution of WC anode into metallic tungsten was evaluated based on the experimental verifications and electrochemical methods. The effects of the main technical parameters, including the cell voltage, electrolysis time and electrolysis temperature, on the dissolved condition of anode were studied and the optimal anode parameters were obtained. It was found that a large electrolytic voltage, high electrolytic temperature and long electrolysis time would be favorable for the dissolved state of the tungsten carbide anode under the same conditions. The cathode product was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the tungsten particles with a diameter of 100 nm could be prepared by this process in a molten salt bath. Linear sweep voltammetry was applied to investigate the dissolution of WC anode, and showed that the WC scrap material could be used as consumable anode to produce tungsten powder. Other electrochemical techniques including cyclic voltammetry , square-wave voltammetry and chronopotentiometry were employed to explore the electrochemical properties of tungsten ion derived from WC anode in LiCl-KCl melts. These results confirmed that electroreduction of tungsten ion in the melts proceeded in one step with four exchanged electrons.